var WebRtcStreamer = (function () {

  /** 
   * Interface with WebRTC-streamer API
   * @constructor
   * @param {string} videoElement - id of the video element tag
   * @param {string} srvurl -  url of webrtc-streamer (default is current location)
   */
  var WebRtcStreamer = function WebRtcStreamer(videoElement, srvurl) {
    if (typeof videoElement === "string") {
      this.videoElement = document.getElementById(videoElement);
    } else {
      this.videoElement = videoElement;
    }
    this.srvurl = srvurl || location.protocol + "//" + window.location.hostname + ":" + window.location.port;
    this.pc = null;

    this.pcOptions = {
      "optional": [{
        "DtlsSrtpKeyAgreement": true
      }]
    };

    this.mediaConstraints = {
      offerToReceiveAudio: true,
      offerToReceiveVideo: true
    };

    this.iceServers = null;
    this.earlyCandidates = [];
  }

  /** 
   * Connect a WebRTC Stream to videoElement 
   * @param {string} videourl - id of WebRTC video stream
   * @param {string} audiourl - id of WebRTC audio stream
   * @param {string} options -  options of WebRTC call
   * @param {string} stream  -  local stream to send
   */
  WebRtcStreamer.prototype.connect = function (videourl, audiourl, options, localstream) {
    this.disconnect();

    // getIceServers is not already received
    if (!this.iceServers) {
      console.log("Get IceServers");

      var bind = this;
      request("GET", this.srvurl + "/api/getIceServers")
        .done(function (response) {
          if (response.statusCode === 200) {
            bind.onReceiveGetIceServers.call(bind, JSON.parse(response.body), videourl, audiourl, options, localstream);
          } else {
            bind.onError("getIceServers " + response.statusCode);
          }
        });
    } else {
      this.onReceiveGetIceServers(this.iceServers, videourl, audiourl, options, localstream);
    }
  }

  /** 
   * Disconnect a WebRTC Stream and clear videoElement source
   */
  WebRtcStreamer.prototype.disconnect = function () {
    if (this.videoElement) {
      this.videoElement.src = "";
    }
    if (this.pc) {
      request("GET", this.srvurl + "/api/hangup?peerid=" + this.pc.peerid);

      try {
        this.pc.close();
      } catch (e) {
        console.log("Failure close peer connection:" + e);
      }
      this.pc = null;
    }
  }

  /*
   * GetIceServers callback
   */
  WebRtcStreamer.prototype.onReceiveGetIceServers = function (iceServers, videourl, audiourl, options, stream) {
    this.iceServers = iceServers;
    this.pcConfig = iceServers || {
      "iceServers": []
    };
    try {
      this.createPeerConnection();

      var callurl = this.srvurl + "/api/call?peerid=" + this.pc.peerid + "&url=" + encodeURIComponent(videourl);
      if (audiourl) {
        callurl += "&audiourl=" + encodeURIComponent(audiourl);
      }
      if (options) {
        callurl += "&options=" + encodeURIComponent(options);
      }

      if (stream) {
        this.pc.addStream(stream);
      }

      // clear early candidates
      this.earlyCandidates.length = 0;

      // create Offer
      var bind = this;
      this.pc.createOffer(this.mediaConstraints).then(function (sessionDescription) {
        console.log("Create offer:" + JSON.stringify(sessionDescription));

        bind.pc.setLocalDescription(sessionDescription, function () {
          request("POST", callurl, {
              body: JSON.stringify(sessionDescription)
            })
            .done(function (response) {
              if (response.statusCode === 200) {
                bind.onReceiveCall.call(bind, JSON.parse(response.body));
              } else {
                bind.onError("call " + response.statusCode);
              }
            });
        }, function (error) {
          console.log("setLocalDescription error:" + JSON.stringify(error));
        });

      }, function (error) {
        alert("Create offer error:" + JSON.stringify(error));
      });

    } catch (e) {
      this.disconnect();
      alert("connect error: " + e);
    }
  }


  WebRtcStreamer.prototype.getIceCandidate = function () {
    var bind = this;
    request("GET", this.srvurl + "/api/getIceCandidate?peerid=" + this.pc.peerid)
      .done(function (response) {
        if (response.statusCode === 200) {
          bind.onReceiveCandidate.call(bind, JSON.parse(response.body));
        } else {
          bind.onError("getIceCandidate" + response.statusCode);
        }
      });
  }

  /*
   * create RTCPeerConnection 
   */
  WebRtcStreamer.prototype.createPeerConnection = function () {
    console.log("createPeerConnection  config: " + JSON.stringify(this.pcConfig) + " option:" + JSON.stringify(this.pcOptions));
    this.pc = new RTCPeerConnection(this.pcConfig, this.pcOptions);
    var pc = this.pc;
    pc.peerid = Math.random();

    var bind = this;
    pc.onicecandidate = function (evt) {
      bind.onIceCandidate.call(bind, evt);
    };
    pc.onaddstream = function (evt) {
      bind.onAddStream.call(bind, evt);
    };
    pc.oniceconnectionstatechange = function (evt) {
      console.log("oniceconnectionstatechange  state: " + pc.iceConnectionState);
      if (this.videoElement) {
        if (pc.iceConnectionState === "connected") {
          this.videoElement.style.opacity = "1.0";
        } else if (pc.iceConnectionState === "disconnected") {
          this.videoElement.style.opacity = "0.25";
        } else if ((pc.iceConnectionState === "failed") || (pc.iceConnectionState === "closed")) {
          this.videoElement.style.opacity = "0.5";
        } else if (pc.iceConnectionState === "new") {
          bind.getIceCandidate.call(bind)
        }
      }
    }
    pc.ondatachannel = function (evt) {
      console.log("remote datachannel created:" + JSON.stringify(evt));

      evt.channel.onopen = function () {
        console.log("remote datachannel open");
        this.send("remote channel openned");
      }
      evt.channel.onmessage = function (event) {
        console.log("remote datachannel recv:" + JSON.stringify(event.data));
      }
    }

    try {
      var dataChannel = pc.createDataChannel("ClientDataChannel");
      dataChannel.onopen = function () {
        console.log("local datachannel open");
        this.send("local channel openned");
      }
      dataChannel.onmessage = function (evt) {
        console.log("local datachannel recv:" + JSON.stringify(evt.data));
      }
    } catch (e) {
      console.log("Cannor create datachannel error: " + e);
    }

    console.log("Created RTCPeerConnnection with config: " + JSON.stringify(this.pcConfig) + "option:" + JSON.stringify(this.pcOptions));
    return pc;
  }


  /*
   * RTCPeerConnection IceCandidate callback
   */
  WebRtcStreamer.prototype.onIceCandidate = function (event) {
    if (event.candidate) {
      if (this.pc.currentRemoteDescription) {
        this.addIceCandidate(this.pc.peerid, event.candidate);
      } else {
        this.earlyCandidates.push(event.candidate);
      }
    } else {
      console.log("End of candidates.");
    }
  }


  WebRtcStreamer.prototype.addIceCandidate = function (peerid, candidate) {
    var bind = this;
    request("POST", this.srvurl + "/api/addIceCandidate?peerid=" + peerid, {
        body: JSON.stringify(candidate)
      })
      .done(function (response) {
        if (response.statusCode === 200) {
          console.log("addIceCandidate ok:" + response.body);
        } else {
          bind.onError("addIceCandidate " + response.statusCode);
        }
      });
  }

  /*
   * RTCPeerConnection AddTrack callback
   */
  WebRtcStreamer.prototype.onAddStream = function (event) {
    console.log("Remote track added:" + JSON.stringify(event));

    this.videoElement.srcObject = event.stream;
    var promise = this.videoElement.play();
    if (promise !== undefined) {
      var bind = this;
      promise.catch(function (error) {
        console.warn("error:" + error);
        bind.videoElement.setAttribute("controls", true);
      });
    }
  }

  /*
   * AJAX /call callback
   */
  WebRtcStreamer.prototype.onReceiveCall = function (dataJson) {
    var bind = this;
    console.log("offer: " + JSON.stringify(dataJson));
    var descr = new RTCSessionDescription(dataJson);
    this.pc.setRemoteDescription(descr, function () {
      console.log("setRemoteDescription ok");
      while (bind.earlyCandidates.length) {
        var candidate = bind.earlyCandidates.shift();
        bind.addIceCandidate.call(bind, bind.pc.peerid, candidate);
      }

      bind.getIceCandidate.call(bind)
    }, function (error) {
      console.log("setRemoteDescription error:" + JSON.stringify(error));
    });
  }

  /*
   * AJAX /getIceCandidate callback
   */
  WebRtcStreamer.prototype.onReceiveCandidate = function (dataJson) {
    console.log("candidate: " + JSON.stringify(dataJson));
    if (dataJson) {
      for (var i = 0; i < dataJson.length; i++) {
        var candidate = new RTCIceCandidate(dataJson[i]);

        console.log("Adding ICE candidate :" + JSON.stringify(candidate));
        this.pc.addIceCandidate(candidate, function () {
          console.log("addIceCandidate OK");
        }, function (error) {
          console.log("addIceCandidate error:" + JSON.stringify(error));
        });
      }
      //   this.pc.addIceCandidate();
    }
  }


  /*
   * AJAX callback for Error
   */
  WebRtcStreamer.prototype.onError = function (status) {
    console.log("onError:" + status);
  }

  return WebRtcStreamer;
})();

if (typeof module !== 'undefined' && typeof module.exports !== 'undefined')
  module.exports = WebRtcStreamer;
else
  window.WebRtcStreamer = WebRtcStreamer;
